Piston



Sept. 3, 1940.

' v. VOSTREZ PISTON Filed Feb. B, 1937 Fig- 3 fig- 2 INVENTOR.

v/cfor Vbs/rez ATTORNE Patented Sept. 3, 1940 UNITED STATES PATEN OFFICEv 4 Claims.

My invention relates to pistons for internal combustion engines andhaving for one of its objects the provision of a two-piece constructionwherein the piston head is supported directly on the piston pin bosses.

Another object of my invention is the provision of a structure whereinthe piston skirt carries only the thrust of the connecting rod.

Another object is the provision of; a piston structure wherein all poweris transferred directly to and through the piston pin bosses.

Another of my objects is the provision of a piston head and skirt sorelated to each other that the skirt may be fitted much closer to thecylinder wall than in the prior pistons, resulting in quieter operationand longer life of the piston.

Another object which I have in View is the provision of a piston havinga head and a skirt of different metals, the metal of the head havinggreater heat conductivity and lighter weight than the metal of theskirt.

Another object of my invention is theprovision of a piston head andskirt which are so united that each is entirely free to expand andcontract individually, thus making possible the use of material oflighter weight and insuring greater strength and reduced wear.

Another object is the provision of a piston skirt having its onlycontact with the piston head at the pin bosses to thus provide bettertemperature control and avoiding the excessive heating of the upperportion of the piston skirt.

Another of my objects is the provision of an integral piston formed bywelding or otherwise uniting the piston head and skirt into a unitary Istructure.

It is also my object to provide a piston head and skirt which may eachbe cast or forged without the use of cores or complicated dies.

Having in view these objects and'others which will be pointed out in thefollowing description, I will now refer to the drawing, in which Figure1 is a-median vertical sectional view of my piston, the section being inthe median planefi of the pin bosses. a

Figure 2 is a bottom plan view of the piston.

Figure 3 is a sectional view. on the line' 3-3 of Figure 1. f

The pistonincludes a head Ill and a skirt II which are provided withribs l2 and I3 respectively. The head Ill and skirt H are each integralwith their ribs, being soformed in the casting process. The head I0 isfurther provided with theusual ring grooves l4. Projecting inwardly fromthe skirt ii are two pinbosses I5 which are in alignment with each otherand diametrically stantially integral relation. The lower portion of thehead I0 is reduced in diameter whereby the head is spaced from and outof direct contact with the skirt, thus reducing the heat transfer to theskirt. This lower portion is also cut away between the areas ofengagement with the bosses, as shown in Figure 3, to further decreasethe heat transfer from the head to the skirt. The head is provided witha pair of upwardly projecting screw sockets 56 for receiving the capscrews ii. In the pin' bosses i5 there are two apertures i8 and 59indiametric relation and aligned. in the pin bosses with respect to thescrew threaded sockets i5.

-The apertures iii are stepped with the upper portions of substantiallythe diameter of the sockets l6 and with the lower portions of a diameterto snugly seat the heads of the cap screws if. The

apertures i9 are of a size to permit the passage therethrough of theheads of the cap screws H.

In assembling the parts, the head and skirt are held together with theapertures 18 and iii in alignment with the sockets and they are thensecured together in this position. The cap screws i! are insertedthrough the apertures i9 and driven into the sockets Hi. In order tomake continuous the inner surfaces of the pin bosses, the heads of. thescrews i'i may be welded or brazed at 20 to not only providecontinuous-surfaces but to unite the head and skirt in integralrelation. If perfectly smooth surfaces are desired, the surfaces of thepin sockets may be machined. As the final step in the assemblage of thepiston, the bushings H are driven into the pin sockets of the pinbosses.

In the above described piston, the head has no contact with the skirtexcept at the piston pin bosses which constitute the sole support forthe head. This "construction distinguishes over those priorconstructions in which the head rests on a continuous annular shoulder.v With my construction I am enabled to use aluminum 'or an aluminumalloy for the head and to employ steel or aniron alloy for the skirt andto thus obtain all of the advantages of a head'of light weight and greatheat transfer without the disadvantages due to the diflicultiesresulting from the great difference in the coeflicients of expansion.

alloy because of the superior wearing qualities of these metals.

My piston has advantages also in their manu- The skirt is preferablymade from steel or an iron iacture and assembly. The head and skirt are'each of simple design' which adapts itself readily to the castingprocess, requiring no complicated dies or molds and requiring theminimum of machining. In the finished product the cap screws areentirely concealed and firmly secured in place without objectionableprojections from any of the smooth surfaces of the piston. This is duelargely to the alignment of the socket 16 with the apertures l8 and I9whereby the cap screw may be introduced through the aperture [9. to beseated in the aperture l8 and the socket l6.

Having thus described my invention in such full, clear and exact termsthat its construction and utility will be readily understood by othersskilled in the art to which it pertains, what I claim as new and desireto secure by Letters Patent of the United States is:

1. A piston. comprising a skirt having integral opposed inwardlyextending pin bosses disposed intermediate the upper and lower ends of nthe skirt, a head having an upper ring-grooved portion of substantiallythe exterior diameter of the skirt and having a lower portion of amaximum transverse dimension less than the interior diam-' eter of theupper end of the skirt and extending downwardly into the latter inspaced relation to the same and seated upon the upper portions of thebosses to support the head directly from the bosses and in spacedrelationto all other parts of the skirthsaid head being formed of ametal having a higher heat conductivity and lighter weight than themetal of which the skirt is formed, and securing means between the upperportions of the bosses and the lower portion 'of the head for securingthe head to the skirt.

2. A piston, comprising a skirt having integral opposed bosses extendinginwardly toward each other with their axes in a plane intermediate the Ytop and bottom of the skirt, said bosses having verticallyalining'openings in the upper and lower walls thereof, a head having aring carrying poramsnn tion at its upper end and having a reduced'lowerportion extending in spaced relation into the upper end of the skirt andseated at its lower extremity upon the upper walls of the bosses, saidlower portion of the head having threaded bores therein registering withsaid openings in the bosses, and screws secured upwardly through theupper walls of the bosses and intosaid bores of the lower portion ofthehead for securing the head to the skirt.

' 3. A piston comprising a, skirt having integral opposed inwardlyextending pin bosses, a head having an upper ring-grooved portion ofsubstantially the exterior diameter of the skirt and a lower portionseated upon the upper portions of said bosses to support the headdirectly from the bosses, said head being provided with a plurality ofscrew threaded sockets projected upwardly therein and said pin bossesbeing provided with apertures in alignment with the sockets of saidhead, screws passing through the apertures of said pin bosses and intothe sockets of said head, and bushings in the pin sockets of said pinbosses and covering the heads of said screws.

4. A piston comprising a skirt having integral openings in the upperwalls thereof, a head having a ring carrying portion at its upper endand having a reduced lower portion extending in spaced relation into theupper end of the skirt and seated at its lower extremity only upon theupper walls of the bosses, said lower portion of the head havingthreaded bores registering with said openings in the bosses, screwssecured upwardly' through the upper walls of the bosses and into saidthreaded bores of the head for securing the head to the skirt, andbushings in the pin sockets of said pin bosses and covering the heads ofsaid screws.

VICTOR VOSTREZ.

